Make sure your installers are experienced and competent (use lifetime caulk inside/out, good R12+ insulation around the window, etc.), since a bad install will blow away any savings you might expect due to air leaks. Check with your local BBB and get some references.

eberry, i thought you are a consumer looking for information yourself? what is lifetime caulk? let me clarify for someone without all the expertise as eberry in the window industry. you did not just here anything about lifetime caulk. no matter which windows you choose for your project you, as the homeowner, must take the time at least once a year and inspect the caulk around your new windows. no manufacturer will cover caulk in a warrantee nor will any installer. it is the homeowners responsibility to correct or reapply caulking as needed. and at some point it will be needed. it will remedy possible problems in the long run. oh yeah i too recommend an r-12 insulation??????? what the ....is r-12 ?? loosely tucking fiberglass insulation aroung all possible areas of a window or using a low expansion foam around a window will work just great. r-1 through r-99 will work just the same.

Yes, there are installers that will cover caulk and waranty it for the life of the window. I know it sounds odd, but I've talked to two window dealers willing to drive out to my house and recaulk anytime the caulk starts to break down on the interior or exterior of the wall (assuming the consumer actually notices interior calking problems).

I will admit "lifetime caulk" is poor phrasing on my part. I've seen caulks advertised like this on the packaging, but it usually just means it is rated as a "long-lasting" product. I don't know how many years 'lifetime caulks" are rated to last, and I doubt there is any certification of manufacturer claims in this reguard.

The most important place place to use good sealing and long lasting caulk is the interior, since it is harder for most consumers to re-caulk internally once the window is on. Caulking on the outside is something any home owner can do as part of regular maintenance.

I don't agree that any R rating fiberglass insulation will provide the same performance to fill any larger airspaces around the window (sometimes there may be none), but I'm happy to be proven wrong. I do agree it needs to be loosely packed, though.

I do not work in the window industry, and don't claim to be an expert. I'm only trying to help others with what I've learned from others in the industry and my own research. I definitely encourage anyone to ignore my posts or try to correct me if they don't agree with me, and I appreciate your concern for providing good information to consumers.

I personally consider that site to be way less-than-perfect as well, but it is the only one I know about that doesn't come (only) from a single company selling windows. Sadly, the DOE and consortium couldn't come up with anything better. One issue I have with the site is the much better efficiency ratings they give to foam-insulated vinyl windows.

Here are my thoughts, if it helps:

- U-Value: Lower is always better (energy star recommends different minimum values for different climates, but most people here will suggest you exceed those minumums as much as your budget alllows). Other factors play into the efficiency area such as install quality and air infiltration rates.

- SHGC: The % of solar heat radiation that passes through the window. You know how your drapes/carpet get hot from sunlight? A low SHGC stops that. Lower SHGC is generaly better in warm climates and for most windows, but not always, as it is dependent on climate, the window facing direction, and any shading. A technical summary of SHGC is here:http://resourcecenter.pnl.gov/cocoon/mo ... ticle/1393

- VT: This isn't as much directly an efficiency issue as a preference issue. It measures the % of visible light that makes it through the glass, grilles, etc. The lower the VT % the darker your house will be. More glass, coatings, etc. on the window will usually reduce the VT, so more efficient windows often have a lower VT, which is a downer for cold climates where there might be less light anyway. Visit a showroow or two and check a few windows when as viewed facing directly to the sunlight or through as clear glass as you can find. Make sure your window's VT is acceptable to you.

Most people seem to think that triple pane argon/krypton, if reasonably priced, is a good option in extreme climates, and I'd say Boston is one of those climates.

Last edited by eberry on Fri Jan 13, 2006 12:01 am, edited 2 times in total.

large airspaces? if you have larger than 1/4" around all sides of that window, you have a window that is mismeasured. now someone is fitting your house to the windows rather then fitting windows to your house. make sure you get the caulking contractors to put that in writing for you.

I guess I wans not precise enough. I didn't say "large airspaces", I said "larger airspaces" and I meant relative to the airspace that might be completely consumed by caulk only (I know some of you prefer minimally expanding foams to caulk, and I can see the reasons why).

I think it is common that even when very carefully measuring a window to be replaced from the outside, the actual cavity when you remove the old window might have too much slack to be consumed by caulk, and in that case, good quality insulation/foam or some combination is very important. I have no problem believing that righ R value insulation is better then low R value insulation for this purpose.

the crack between the window and the old frame can not tell the difference between r-11 and r-13,19,30 or whatever. fiberglass insulation.....oh forget it i give up. if you think it makes a difference okay then.

If I'm wrong (and I admit I may well be for a reason I don't comprehend yet) and you buy some high R-value insulation, you're only out a few dollars with no benefit. I do agree with you the important thing is having some type of insulation/caulk/etc. in the gaps. I just believe higher R values should help a little bit more - and when you're spending thousands on windows, the little details like this (good caulk, insulation procedures, etc.) should help point to a good installer.

I also updated my profile here, so it is clear I am not a window expert by trade. Maybe that will help some people interpret my posts relative to my only indirect experience in the industry.

In short, it seems that insulation R-values are too hard to predict when stuffed in window frames and can decrease dramatically, so using higher R values for fiberglass insuation may not pay back (sorry for suggesting this). What appears important is that the material you use to seal the window seals the cracks well and also has a high R value for the intended use (window foams are suggested as good alternatives to fiberglass).

THD: "the truth on triple pane windows is that ou will ahve better inside glas temperature as the third pane is nothing more than a heat reflective film "

That would be Heat Mirror... not a true triple-pane with three pieces of glass.

THD: "I fell it is garbage compared to a *very* good dual pane with argon and low e."

If that's how you "fell".. fine, but the NFRC disagrees with you by showing about 20-30% lower U-factors with the top-of-the-line triple pane, and Heat Mirror Products verses double-panes. Is it the perfect fit for everyone? No, but it is effective at increasing performance.

THD: "The reason is the cost:
For an average $3-500.00 MORE per window at time of purchase..
and say your heating and colling costs run avg of 200 per month --
You will save around 19 dollars and change per year for the payback on the inital investment. (ouch!)"

Some of the triple-pane, double Low-e, Krypton products(referred to as "Superwindows" by the USDOE), can actually show a Net energy gain instead of a loss. I don't suppose the instructor transferred from Lawn and Garden had that information available. Many dealers of these products come in less than the HD bids for double-panes and have better trained installers to boot.

Now, for your cost savings estimates. I have no doubt you plugged in a couple of numbers into an energy-savings calculator online which is extremely innaccurate and is not based on an overall home's performance. These calculators were funded by the government to show homeowners that "a" difference can be made by increasing energy-efficiency... and are not in any way to be considered accurate in determining overall impact of any improvement. There is not a calculator online or anywhere else that can even come close to an accurate estimate of ANY improvement without performance testing a specific structure.

THD: "the truth on triple pane windows is that you will have better (HIGHER) inside glass temperature as the third pane is nothing more than a heat reflective film "

That would be Heat Mirror... not a true triple-pane with three pieces of glass.

RESPONSE-- AND THIS HEAT MIRROR WOULD BE MADE OF?

THD: "I feel it is garbage compared to a *very* good dual pane with argon and low e."

If that's how you "feel".. fine, but the NFRC disagrees with you by showing about 20-30% lower U-factors with the top-of-the-line triple pane, and Heat Mirror Products verses double-panes. Is it the perfect fit for everyone? No, but it is effective at increasing performance.

THD: "The reason is the cost:
For an average $3-500.00 MORE per window at time of purchase..
and say your heating and colling costs run avg of 200 per month --
You will save around 19 dollars and change per year for the payback on the inital investment. (ouch!)"

Some of the triple-pane, double Low-e, Krypton products(referred to as "Superwindows" by the USDOE), can actually show a Net energy gain instead of a loss. I don't suppose the instructor transferred from Lawn and Garden had that information available. Many dealers of these products come in less than the HD bids for double-panes and have better trained installers to boot.

Now, for your cost savings estimates. I have no doubt you plugged in a couple of numbers into an energy-savings calculator online which is extremely innaccurate and is not based on an overall home's performance. These calculators were funded by the government to show homeowners that "a" difference can be made by increasing energy-efficiency... and are not in any way to be considered accurate in determining overall impact of any improvement. There is not a calculator online or anywhere else that can even come close to an accurate estimate of ANY improvement without performance testing a specific structure.

This is in fact the beauty of an open forum -- This is AWESOME to have debate and differing opinions!!

however, I will stand true to the fact that the energy savings payback is FAR too Slow and too little on a triple pane window compared to a superior dual glazed product. (not all dual glazed windows can meet this standard).

Indeed this is my opinion and how I stated it is from factual data "AVERAGES" that may be not-so-well-known facts. Please - read on..

Again like you said - unless a comprehensive study of the individual structure is completed this is just a "rule of thumb" as mentioned - and I did not use some online calculator to come to this data.

You are correct on the U-factor being lower (depending upon the product) - but what is that going to do for me (ie an average homewoner)? and the test results do prove it -but what does it mean in comparison????

In my personal opinion, I do not feel that a heat reflective mirror (used to do what again - make the inside glass temperature feel warmer?) and provide's some impressive differences in u-factor ratings, condensating temperatures, etc., etc. would be worth the up-front costs to the "Average" homeowner as I can and will validate:

So now: Let us take a closer at those spec's - This time in laymans terms such that just about anyone can understand without further research or requiring a whole structure test to figure this one out:

Heat transmission facts on window types:

A clear single pane of glass transmits heat at the rate of 90+/-%

An insulated glass unit (with natural air-no gas + single strength - the average new construction anderson window for instance) transmits heat at the rate of 67-75+/-%

The bottom line is that *real* savings (defined to be payack on the original investment) are found when stepping up to the plate and getting at least a superior dual glazed window - do not economize on your home - save that for a car that you are going to trade in 3 years or so). Hence, it remains a proven act over and again - buy quality and save.

Furthermore, if one could afford the luxury of a triple pane window and feels that it is more important to save another 3% on energy efficiency - far be it from me to deter them in any way as I am also energy conscious here as well. (unfortunately there are not enough lottery winners in the real world to be able to afford this sort of slow payback on investment).

So the real question (and my point to begin with here and originally) once again becomes: "Is it really worth $300-500.00 (minimum cost in addition) on an UP FRONT investment to save 3 +/-% on the heat pass through over time?"

I don't know about your calculator - but mine says this is not tha great of a payback.

Perhaps now the information is not so misleading after all and hopefully clairifes what I originally posted...

THD50, So far your response to any question seems to be a bunch of jibberish. Why can't you answer a question with an answer that doesn't skirt the issue. As I follow these posts I also agree your answers are falsely based. A true triple pane glazed IGU has three sheets of glass. Others add the Heat Mirror Film you brought to the plate. Your answer to his question still follows the glass with Heat Mirror film rather than glass. Your statistics don't reflect the use in Northern Climates where it gets down to -50. Triple pane glass saves you a lot more than you've calculated. Instead of posting the results I'll wait to see your answer.

Remember, your the one who stated your only here as an information provider for the consumer. If you are then you will post your results in a way that they can understand. Ounce they find your answers lack validity, you will disappear into the night like many others have. Seems to me there was another individual that posted from a Home Depot store in Texas awhile back. Seems to have a lot of similarities!!!